Vessels employed in and licensed for the coasting trade shall be exempt from the duty of employing a pilot, and the vessels as well as their masters, owners, agents or consignees, shall be exempt from the duty of paying pilotage, half-pilotage or any penalty whatsoever, in case of their neglect or refusal so to do, except ships or vessels under register, bound to or from the States or territories of the United States on the Pacific Ocean; but a coastwise vessel, voluntarily taking a pilot, shall pay a fee which is no more than the fee for pilotage as prescribed in the case of a vessel bound to or from a foreign port.